Releasable drill collar



' March 22 1927.

1,621,583 T. A. CREIGHTON y RELEASABLE DRILL COLLAR Filed Nov. 25, 1925 INVENTOR. 77/0m/1s- A. CREIGHTO/V.

Patented Mar; 22,1927.

TES

UNITED STA;

PATENT o icE.

RELEASABLE DRILL COLLAR.

Application filed November 23, 1925. Serial No.-70,868. I

An object of my invention isto provide a drill collar which may be readily released from the bit when said bit becomes fastened in the well, so that the drill tubing may be removed from the well. A v

Another object is to provide a drill collar which may be released from the bit when said bit becomes fastened in the well so that the drill tubing may be rotated 'inde-- pendent of the bit and said tubing may also be moved longitudinally a short distance.

A further object is to provide a drill collar which may be released from the drilling position on the bit, and which may then impart a jar to the bit to release said bit 'if it is fastened in the well, and mayagain I cent its lower end with a steeppitch right.

be returned to" the drilling position, on resuming cutting.- Other objects advantages and features of nvention may appear from the accompanying drawingthe subjoined detailed description and appended claims.

In the drawing illustrating my invenhollow pin 3 is securely fastened. This pin is preferably screwed into the housing 2 and then welded in place. The lower section of the drill tubing 4 screws on to the pin 3, with a tight friction joint.

A safety collar 5 screws into the lower end of the housing 2, forming therewith the tight joint 6. a

The collar 5 is internally threaded' adjahand thread 7, and a hollow pin 8 is formed with'threads 9 which screw intothe collar Thepurpose of these threads will be further described. The lower end of the pin 8 is formed with a box 10 into which the bit 11 is adapted to tightly screw. i A release nut 12 is internally threaded with a left hand thread 13, and the pin 8 is formed with threads 14 adjacent its up-- I tuated locking dog per end whichscrew therein. The upper end 15 of the pin projects through and above the nut 12. The nut is of less diameter than the housing 2 and is free to move therein. A cup washer 16 is secured'to the upper surface of the nut 12 by a retainer 17, said washer reventing the passage of dirt, water, etc.,' etween the nut and hous-fl ing 2, which dirt may obstruct the free movement of the nut. r

As shown in Fig. 1 thedrill collar is in cutting position and right hand rotation of,

the-tubing 4 will cause the bit 11 to rotate andeut. It may, be desirable to prevent this right hand rotation from too tightly screwing the threads 9 into the collar 5; For this purpose I may employ a spring ac- 18 which is mounted in a recess 19 in the box 10. The upper face 20 of the dog 18 is cut aslant and fits into. a notch 21 in the lower surface of the collar 5. Thus when the dog 18 falls into the notch 21 further rotation of thef collar relative to the box 10 is prevented and the threads 9 will notbindJ Due to the slope .of the upper face of the dog the collar 5 may be freely unscrewed.

Now ifthe bit 11 becomes fastenedin the hole, and-can notbe moved left hand rota;

tion of the tubing 4 will unscrew the collar 5 from the threads 9. Due to the steep pitch of thethreads 9, they will not readily bind' and will unscrew. before any of the other joints in the tubing 4 or drill collar 1. The pin 8 is made such a length that a considerable amount-of longitudinal movement of the tubing 4 is possible before the upper surface "of the collar 5*strikes the nut 12.-

The sudden striking of the collar against the nut imparts a shock to the pin 8 and bit 11 which may serve to jar the bitloose. However if this is not successful thetubing 4 may be released from the bit as follows:

.- Lugs 22 depend from the nut 12 and .are

adapted to fit into notches 23 in the upper face of the collar 5, thus coupling the nut ,to the collar and to the tubing 4. Right hand rotation will now unscrew the left hand threads 14 and thus release the tubing, housing 2 and collar 5 from the pin 8 and bit 11. A separate tool may now be employed to release and recover .bit, and pin.

Having described my invention I claim- I. A drill collar comprising a housing, an elongated pin, a bit adapted'to be secured to the pin, releasable means connecting said pin and said housing, a: nut on said pin, said housing being adapted for longitudinal movement along said pin when said releas able means is released and means coupling be removed from said be released from the pin.

said nut and said h'ousing whereby said nut pin to release said housing from the pin.

2. A drill collar comprising a housing, a pin extending into said housing, steep pitch threads on said pin screwing into said housing, a bit adapted to besecured to said pin, said threads being adapted to release said pin from the housing, anut on said pin, said housingbeing adapted to. engage said nut to limit the longitudinal movement of said housing on the pin, and means coupling said housing and said nut whereby said nut may 3. A drill collar comprising a housing, an elongated pin, releasable means coupling said pin to said housing, anut threaded on to said pin, and means coupling said nut and said housing whereby said nut may be r'unscrewedwhen said releasable means is areleased. 4. A drill collar comprising .a housing, an elongated pin,- a nut threaded onto said pin, releasable means coupling said pin to said nut and said housing whereby said nut may be unscrewed when said releasable means is released, said coupling means comprising lugs depending from said nut, and said housing having recesses therein adapted to receive said lugs. A v 5. A drill collar comprising a housing, an .elongated pin, releasable means coupling said pin and housing, a nut threaded onto said pin, lugs depending from said nut, said housing having. recesses therein, adapted to engage said lugs tounscrew the nut when said releasable means is released, and a cup washer on top of said nut.

In testimony whereof I hereto affix my .signature.

THOMAS A. CREIGHTON. 

